Traffic-control system for radio broadcast distribution



June 5, 1928. 1,672,374

E. E. CLEMENT TRAFFIC CONTROL SYSTEM FOR RADIO BROADCAST DISTRIBUTION w k Q 0% Q Q E3 u 3% w ER QSE %1U J T6 1 I I L I Farm znzrcu T12 'J 1323 3i E i gwuentoz Patented June 5, 1928.

NlTED STATES 1,672,374 PATENT OFFICE.-

EDWARD E. CLEMENT. OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR T0 EDWARD F. COLLADAY, OF WASHINGTON, DISTRICT OF COLUMBIA.

TRAFFIC-CONTROL SYSTEM FOR RADIO BROADCAST DISTRIBUTION.

Application filed April 17, 1925. Serial No. 23,880.

My invention relates to radio broadcast distribution systems and more particularly to trafiic control.in such systems and has for its object the provision of a combined telephone exchange system and radio broad cast distributing system with means controlled froin subscribers stations for automatically differentiating between the two kinds of service.

In my copending applications, Serial No. 754,460, filed December 6, 1924-, and Serial No. 10,533, filed February 20, 1925, are disclosed combined telephone and broadcast service systems in which a subscriber may effect ditlerent signal indications at the central ofiice for indicating respectively the different kinds of service wanted, the differentiation between signals being made at the central oflice by human intelligence. The present invention is directed to this provision at the central office of circuit closing means differentially responsive to different signals sent from a subscribers station for automatically differentiating between the kinds of service connection to be made with the subscribers line.

The invention is illustrated in the accompanying'drawing, which is a diagram showing the necessary apparatus and operations of. the circuit closing means at the central station and the differential controlling means at the subscribers station.

Referring to the drawing in detail, C represents the central station, and S a subscribers station connected with the central station over line wires 1.-2, the vertical dotted lines indicating the distance between the stations. At the central station, are differentiating line relays TR and BR, the relay TR being the telephone line relay, and BR a broadcast service line relay. The telephoneservice relay TR is arranged, as usual, to respond to a closure of the line circuit and close a normally open contact 3 in turn controlling the usual telephone line signal or line switching appartus, not shown, through the telephone control circuit TC which With a pair of telephone service line multiples TM, leads to the telephone switchboard, not shown. Similarly, the broadcast service line, relay BR operates upon energization to close its normally open contact 4 controlling a broadcast service control circuit BC which with a pair of broadcast service, line multiples BM leads to a radio service switchboard or switchin device not shown, but which may be 0 any suitable type having means for connecting a source of broadcast matter with the multiples RM and having signaling or switching means controlled over the control circuit BC, such for example, as the broadcast service switching apparatus disclosed in the copending applications above referred to. To render the broadcast service relay BB responsive only to a characteristic condition produced at the subscribers station, it is madein the form of a harmonic relay with a reed supported armature 5 responsive to a periodic variation of current in the windings of the relay magnet and not responsive to a steady How of current. Both line relays TR and BR connect -with the line through normally closed contacts, of the usual cut-ofi' relay, controlled in the usual manner through the test thimbles or sleeves of the associated line 'acks as well understood by those skilled in the art.

At the subscribers substation S are provided the usual transmitter T, receiver R,

- switohhook H, ringer Q, condenser E and induction or boost-er coil I having the primary and secondary windings p and s,'respectirely. These apparatus elements are connected according to standard practice, that is, the ringer Q, is normally connected across the line 1..2 in series with the condenser E, while the switchhook contacts are arranged, upon the raising of the receiver from the switchhook, to connect the primary winding p and transmitter T in series across the line and connect the re-- ceiver R in a local series circuit with the secondary a, condenser E and transmitter T. Also at the subscribers substation is a broadcast receiving set BS arranged as an extension set connected to the telephone set through conductors 6, 7 and 28. This broadcast receiving set consists of a loud speaker unit 9, shunted transmitter 10, and a starting button 11. The starting button being arranged upon actuation to connect the loud, speaker unit and the shunted transmitter with the line through the coil I and condenser E in place of the receiver R and transmitter T. respectively, as connected by the switchhook. Thus upon actuation of the starting button 11, the shunted transmitter 10 and primary coil p are connected in series across the line while the loud speaker unit ably of the harmonic or tuned reed type capable of operating at a given periodicity, which is arranged to be connected across the line through a normally open key or push button 14 by way of conductors 15-46. This push button is reterably situated near the extension set Bk and to enable this to be done with a minimum number of extension leads from the main telephone set, the conductors 1516 may be connected to the binding posts 1718 instead of directly to the line conductors 12, which would include the primary winding 7) in circuit but with no detrimental effect on the operation of the system. i

In operation, a subscriber at substation S desiring a telephone'connection, raises his receiver R off the switchhook H which, as in standard practice, closes his line circuit and energizes his telephone line relay TR at the central station. The energizing circuit-of relay TR may be traced from the common battery B through circuit elements TR, 1, p, H, T, 2 and back to battery B. Energization of the relay TR closes its contact 3 which closes a telephone control circuit TC leading to the telephone switchboard for the purpose of controlling the usual line signal or line switch not shown, in response to the proper and usual functioning of which the subscribers line 1-2 is connected with the telephone switchboard through telephone multiples TM, the line relays TR and BR disconnected from the line through the actuation of the cut-oft relay and the line supplied with current through suitable battery teed devices not shown, all in accordance with'known telephone practice as understood by those skilled in the art. The telephone set at the substation S is then connected for telephone conversation over the line, the transmitter T and primary winding 7) of the booster coil I being connected in series across the line, 1-2 through the contacts of switchhook H, while the receiver R is connected in a. local series circuit including a secondary coil 8, condenser E, transmitter T and contacts of switchhook H. At the end of the telephone conversation, the subscriber hanging up the receiver opens the line circuit at the switchhook contacts, clearing his line in the manner usual in telephone practice.

When the subscriber at substation S de sires broadcast service, he actuates key 14 to close its contacts which closes the energislng circuit of the harmonic electromagnetic vibrator 13 and causes a harmonic intermittent current to flow over the line through lay BR is a harmonic relay arranged to respond to the given periodicity at which interrupter 13 operates, it causes the arma ture 5 to vibrate and maintain the contact 4 closed, in a. manner that will be under-stood by those skilled in the art, which closes the broadcast service control circuit BC leading to and controlling line signaling or switching apparatus at the broadcast distributing switchboard. This causes the subscribers line 1--2 to be connected through the broadcast multiples RM to a source of broadcast supply not shown, and also causes the relays BR and TR to be disconnected from the line through the operation of a suitably arranged cut off relay not shown but which may be like that shown and described in the copcnding' applications above referred to. ll pon becoming so connected, the subscriber'ma v connect his broadcast receiving set BS by actuating, the button 11. This connects the primary winding 1) of the induction coil I across the line by way of circuit elements 1, p, T, 20,- 21, 12, 6, and 2. so that broadcast matter coming over the line 12 is induced in the secondary winding s and operates the loud speaker unit 9 in the local series circuit including the ele ments 3. 8, 9, 21, 12 6. 2 and E. When the subscriber desires to discontinue the broadcast service, he releases the starting button 11 to open the contacts 20 and 21 which opens the line circuit 12 resulting in a disconnection of the source of supply of broadcast matter from the line at the broadcast distributing switchboard through means responsive-to a prolonged opening of the line circuit after service connection, as disclosed in my copending applications above referred to.

It will he understood that the cut-off relay hcrctotore referred to cuts off both relays TR and ER when the line is in use for either telephone or broadcast service. The switching apparatus connected to line multiples TM and BM may in either'or both cases through circuit elements a be of the automatic type and to operate the arate from the telephone. The circuit connections of these parts 13 and 14 may then be varied specifically as described for convenience, so long as the effect is to bridge them across the line in calling as shown. For example they may be included in the telephone transmitter bridge, which would bring them across the terminals 17-18 in eflect, without departing from the principles of the circuit shown.

What I claim is:

1. In a combined common battery telephone exchange system and broadcast distributing system having a central station and subscribers stations connected therewith over wired lines, both systems operating within the range of audio frequencies with a telephone set and a broadcast receiver at each subscribers station and a telephone switchboard and a broadcast distributing switchboard at the central station for furnishing the subscribers with telephone and broadcast service over their respective wired lines the combination of automatic differential traflic control means comprising a telephone line relay and a broadcast service line relay individually associated with each subscribers line and each controlling circuit leading to said telephone. and to said broadcast distributing switchboards respectively. and separate means at each subscribers station associated with the telephone set and with the broadcast receiving setrespectively for differentially controlling the energization of said associated relays, the telephone receiver of the telephone set, and the telephone receiver or loud speaker of the broadcast receiving set being interchangeably connected to the line through the same circuit elements, and being equally responsive to all audio frequency waves coming oyer the line.

2. In a combined common battery telephone exchange system and broadcast dist-ributing system having a central station and subscribers stations connected therewith over wired lines both systems operating within the range of audio frequencies with a. telephone set and a broadcast receiver at each subscribers station, and a telephone switchboard and broadcast distributing switchboard at the centralstation for furnishing the subscribers with telephone and broadcast service over their respective wired lines; the combination of a line identifying circuit at the telephone switchboard-for each line, a line identifying circuit at the broadcast distributing switchboard for each line, and separate means at each suhscribers station associated with the telephone set and'with the broadcast receiving setrespectively for selectively causing the energization of said ditterent line identifying circuits, the telephone receiver of the telephone set, and the telephone receiver or loud speaker of the broadcast receiving set being interchangeably connected to the line through the same circuit elements, and being equally responsive to all audio frequency waves coming over the line.

3. In a combinedtelephone exchange system and broadcast distributing system having a central station and subscribers stations connected therewith over wired lines, both systems operating within the range of audio frequencies, with a telephone switchboard and a broadcast distributingswitchboard at the central station for furnishing the subscribers with telephone and with broadcast service respectively over their respective wired lines; the combination of a telephone service relay and a broadcast service relay at the central station individually associated with a subscribers line, a telephone set and a broadcast receiving set at each subscribers station and a. pair of controlling means at the subscriber's station, one for each relay associated with said sets and each operable in the use of its set to effect an actuation of its associated relay only the telephone receiver of the telephone set, and the telephone receiver or loud speaker of the broadcast receiving set being interch'angeably connected to the line through the same circuit,elements, and being equally responsive to all audio frequency waves coming over the line.

4. Ina combined telephone exchange and broadcast distributing system, a central station containing a telephone switchboard and a broadcast distributing switchboard, and a subscribers station containing a telephone set for conversational purposes and a broadcast receiving set, each comprising a receiver and a transmitter of standard type and both adapted to be connected to line through the same induction coil and circuit connections therefor means to supply broadcast pro grams through the broacasting switchboard at audio frequencies. a pair of differential relays at the central station for each line, one responsive to continuous currents over the line and of standard type to control signal circuits to the telephone switchboard, and the other responsive to variable signaling currents only and controlling signaling circuits to the broadcast service switchboard, switching and. signaling means at the subscribers station for the telephone setand separate switching and signaling means for the broadcast receiving set, each adapted to connect its associated set with the line and to affect the 'appropriaterelay at the central station to produce a telephone signal or a broadcast service signal at will.

5. In a combined telephone exchange and broadcast service system, a central station and a subscribers station and line wires interconnecting them, a telephone switchboard and a broadcast switchboard at the central station with line multiples connecting the line with each of them, and a combined telephone and broadcast receiver at the subscribers station comprising a telephone trans1nitter and a booster coil adapted to be connected across the line with the telephone receiver in the secondary circuit of the booster coil for telephonic communication. and a broadcast receiver or loud speaker adapted to be con nected in the secondary circuit of said booster *coil across the same terminal connections as tion and subscribers stations and line wires interconnecting them. means at said central station for efi'ectiug connection for telephonic interconununication between the sul'iscribers' lines, means also at the central station for supplying broadcast service tothe. subscribers lines within the range of audio frequencies. means at the sul'iscriber's station to receive and transmit telephonic currents for intereomnnmicating purpores. and other means for receiving audio frequency broadcast currents. a booster coil and talk ing condenser common to the telephone set and to the broadcast service, and switching means and signaling devices associated with the telephone set and the broadcast receiver respectively. adapted to differentially con trol signaling circuits at the central ottice to determine selectively the character of the service desired.

In testimony whereof I hereunto afiix my signature.

EDW'ARD E. CLEMENT. 

